The invention relates to a rotary tool, in particular a drill, with the features of the preamble of claim 1. The invention furthermore relates to a cutting head for said rotary tool.
The rotary tool, in particular a drill, is what is known as a modular rotary tool which extends in an axial direction along an axis of rotation and which comprises two coupling parts, namely a carrier and a cutting head, wherein the cutting head is attached to the carrier so as to be exchangeable. For this purpose, the carrier usually comprises on its end surface two opposite fastening webs which are separated from each other by means of flutes and by means of which a pin receiving means is delimited. A coupling pin of the cutting head is inserted into this pin receiving means. This is carried out by turning the cutting head around the axis of rotation relative to the carrier. During said turning, a clamping connection between the cutting head and the carrier is formed so that the two coupling parts are held together in a clamping manner. In particular, no additional fastening means (such as screws or the like) are arranged therein. The pin receiving means of the carrier comprises inner shell surfaces and the coupling pin of the cutting head comprises outer shell surfaces, which shell surfaces reciprocally interact with each other. Torque sections respectively corresponding to one another for transmitting a torque on the one hand, as well as clamping sections corresponding to one another for transmitting a radial clamping force on the other hand, are formed on the inner shell surfaces and on the outer shell surfaces. In the connected state, these sections respectively abut against one another in pairs.
Such a rotary tool can be learned from DE 10 2012 200 690 A1, for example. The present invention relates to a development of the rotary tool described therein.
In the coupling connection known from this prior art, the torque sections as well as the clamping sections on the coupling pin and on the carrier are arranged successively in the circumferential direction. The coupling pin has an approximately cuboid design, wherein sections are cut out from the cuboid shape by means of flute sections. For axial tightening and an axial pull-out lock, either the clamping sections corresponding to one another and/or the torque sections corresponding to one another form a dovetail connection. The respective sections are therefore oriented in a diagonally inclined manner with respect to the axis of rotation.
A modified embodiment variant of the coupling connection to be learned from DE 10 2012 200 690 A1 is to be learned from DE 10 2013 205 889.6, which was not published at the time of application. Here, the torque sections as well as the clamping sections are arranged staggered in relation to one another in an axial direction so that either torque sections or clamping sections are formed at an axial level. In this embodiment variant, a dovetail connection is also formed by diagonally inclined torque sections or clamping sections to achieve axial tightening and to prevent pulling-out in an axial direction.
A positive lock effective in an axial direction is formed by means of such a dovetail connection known from the prior art. This is made possible due to the specific fastening method with the turning of the coupling pin of the cutting head into the pin receiving means of the carrier.
Another similar coupling connection in a drill can be learned from U.S. Pat. No. 6,582,164 B1. In this case, webs protruding radially outward are formed on the outer shell surfaces of the coupling pin, said webs being screwed into a corresponding recess in the pin receiving means in the manner of a thread. The shell surfaces of these threaded webs are arranged in a diagonally inclined manner with respect to the axis of rotation for easy screwing-in.
Finally, another coupling connection can be learned from U.S. Pat. No. 7,070,367 B2, in which once again webs are formed on the outside of the coupling pin, said webs being arranged helically and forming a screw thread by means of which axial tightening of the cutting head in an axial direction takes place during screwing-in. The helical web comprises roof surfaces diagonally inclined with respect to the axis of rotation.
In the coupling connections described so far and known from the prior art, the coupling pin is respectively completely enclosed by the pin receiving means, i.e. by the two opposite clamping or fastening webs, so that both the torque sections and the clamping sections are enclosed by the fastening webs.
In contrast thereto, coupling connections are also known in which the torque sections are not enclosed by the clamping webs but rather extend in the radial direction to an outer circumferential line of the rotary tool so that a circumferential side of the coupling pin is flush with a circumferential side of the carrier in the area of the torque section. A coupling connection of this type can be learned from DE 10 2012 212 146 A1, for example. In this embodiment variant, the surfaces corresponding to one another of the torque sections are once again formed in a diagonally inclined manner in order to prevent pulling-out in an axial direction.
Overall, the known coupling connections are characterized by a complex geometry, which is sometimes very complicated with respect to the production process.